So this actually seems to be a popular topic and a real need that people have brought up to NVIDIA and AMD. Nvidia even acknowledged putting this as an option but I feel like they will ignore it as it's "Too Simple".

Basically, for those who own 4k monitors or even 1440p monitors, if you are playing 1080p videos (full screen) or 1080p games (because your GPU can't run at 60fps in native) , then you are going to be viewing a blurry mess due to the crappy default bilinear interpolation upscaling method for ALL monitors and GPU uses.

So i was wondering if it's possible for wrappers (eg. Reshade) to render the 1080p to upscale via different methods in order to provide an optimal experience for 4k users.

Nvidia has a feature called "Quality Upscaling" that tells the driver to use Lanczos filtering instead of Bilinear when showing 1080p content on 1440 or 2160 displays. It's not visible in the Nvidia control panel, you need Nvidia Inspector to enable it.